This study estimates productivity changes of Korean fossil-fueled power plants incorporating changes in CO2 emissions. The study derives a Törnqvist-type productivity index where the pollutant is incorporated as an undesirable output. The shadow price of pollutant, which is required forcalculating the index, is estimated based on the duality between a revenue function and an output distance function. Productivity changes are measured with both the estimated shadow prices and the actual trading prices of CO2 in the EU-ETS. The results show that productivity change measurement is highly dependent on the choice of shadow prices. The study also investigates the impacts of policy focus on the productivity measurement. The policy target is either to reduce emission itself or to reduce pollution intensity. Our study shows that productivity measurement is dependent on the choice of policytargets as well.